This invention relates to an arrangement for the deployment of towed aircraft decoys.
There are two basic types of aircraft decoy, self contained and controlled. The self contained decoy can be deployed by a simple tether-wire dispenser. The tether-wire is simply a high tensile wire, probably multi-stranded, and is contained in a simple pay-out dispenser. For decoys which are to be deployed at high aircraft speeds, e.g., at Mach 1 or above, the deployment apparatus should include means for decelerating the separation speed of the decoy as the tether-wire pays out to prevent undue snatching at the moment of maximum deployment. A controlled decoy requires to be tethered to the towing aircraft via a tether cable which not only tows the decoy but can carry an electrical and control cable.
Whereas dispenser techniques may be suitable for small independent decoys, which are tethered by steel wire ropes, this may not be possible where electrical, electro/optical or optical links are required to be connected to the aircraft when the decoy is powered and activated directly from the aircraft. In such a case it may be necessary to deploy the tether from a cable reel.
Deployment from a cable reel has the advantage that no torsional twists will be imposed on the tether and the electrical or optical units it will contain. It should be noted that for every turn in a dispenser coil a backtwist is imparted on the tether as it deploys. Such torsionally imposed backtwists may be undesirable for the system's operational requirements.
However, deployment from a cable reel required solutions to:
(i) A method of decelerating. PA0 (ii) A method of retracting the decoy after deployment. PA0 (iii) Provision of transmission lines from the rotating reel to the signal processing unit on the aircraft.
Whereas slipping clutches and similar devices are obvious solutions to the deceleration problem, such devices are somewhat complex and are not self contained as a single package.
It is already known to construct cable reels embodying a spiral spring arrangement. See for example British Patent No. 1590160. In that instance a printed circuit spring acts not only as a cable deployment device but also as an electrical connection between the rotating spool and the stationary shaft.
However, in the field of electronic control and signalling it is becoming practical to utilize optical fiber transmission in place of electrical transmission via metal conductors, the signals being multiplexed onto a single optical fiber. Nevertheless, difficulties arise in coupling a tether-wire incorporating an optical fiber in a rotating cable reel with the stationary shaft on which the reel is mounted. One possible solution is to use optical slip-rings, but this is not regarded by the applicants as a satisfactory solution. Optical rotary joints are not currently available for single mode fiber.